mtnman82

Hi. I have an '03 C230k ss with 51K on the odometer. About 2 hours into a trip Upon stopping for a break, I noticed the car idling very roughly. I drove the car another 30 minutes (after sitting for ~ 30 minutes), car drove fine, but still have the idle problem, however the 'check engine' light came on. I decided to abandon the rest of the trip and come home and rented a OBDII scanner. When I came out of the Autozone with the scanner to drive home, the check engine light was now off, but the car was still idling very rough. Plugged the scanner in once home and got codes P0301, P0302, P0303, P0304, which according the scanner means a misfire was detected in cyl's 1, 2, 3, & 4.

Soooooo, where do I start? Anyone have a similar experience? And, what was the cause if so? My nearest dealer is over 2 hours away, so I'd rather not deal with that if I don't have to. I know how to turn a wrench ... just need to find out what's wrong .....

Anyone???? I'm thinking it'd be great thing to add some more technical threads to this forum ... this being one of them. Thanks in advance!!!

C230 Sport Coup

Someone had this recently and they ended up replacing the head.
Another reason to hate on the M271. Seems a lot of heads have to be replaced due the valves not seating correctly.
I hope you bought the extended warranty.....
If it was just one, it would likely be a coil pack..
check your plugs. That won't cost anything.
They could be fouled. But likely the fouling would be the result of something else.
Still, you'd have a clue to follow. From there you could clean the maf, check the air filter etc. Good luck.
See recent thread from another M271 owner where some hose was clogged causing it to run rough, but no codes.

EDIT: I just remembered I think one guy here had this very recently, and had his fuel injectors cleaned professionally (STF) and it cured it.
Maybe put in some Techron and see what happens (and check the plugs first, might as well replace them, NGK Iridiums).
Maybe you got some bad gas. Did you fill up shortly before the problem occurred?

Buellwinkle

Wow, you made the mistake of keeping the car past it's expiration date, 4 years or 50k miles. Misfires are typically caused by one of to things, not enough fuel, not enough spark. If you got this error on one or two cylinders, I would suspect spark plug, coil pack or fuel injector but it would be rare that all 4 cylinders would have bad spark plug, coil pack or injector. Sooo, first thing i would look at is fuel pressure at the rail, should be close to 4 bar or 50psi as it could be a weak fuel pump, dirty fuel filter, fault fpr. Cleaning the injectors properly (not throwing a can of cleaner in your gas tank, that does very little) can't hurt, I like to get it done every 50K miles and I notice a little performance improvement.

What can also cause a lean condition and rough idle is a vacuum leak. This usually throws a lean trim error in addition misfires but it maybe enough of a leak to cause problems but not bad enough to trigger a code. What you may want to check with your scanner is for pending codes. These are codes that haven't yet reached their treshold but still occurred and look for a p017x that may reflect this condition. Also it could be a dirty MAF, same as vacuum leak in terms of effect. MAF is usually the easiest to fix and you should clean it every 50K miles anyway, search the forum for a how too but a can of MAF sensor cleaner is only $6.

mtnman82

Thanks for the reply, C230 sport coupe!!! Nope, did not buy the extended warranty ... seriously considered it, but the one we needed (w/rental car - we live 2+ hours from dealer) would have been $4K, and we needed to have a new heating/AC unit put on our roof at the same time, so talk of the extended warranty kind of just stopped .....

I don't think it was bad gas - but I could be wrong. I'm lucky enough to have a VP racing fuels gas station a few miles away and always fill up there. That doesn't guarantee anything though, of course.

I'm really, really hoping it's the fuel filter (where is it on one of these guys?) or the plugs/wires. I suppose I'll have to replace the coil packs too, just to be sure.

I'd be really, really bummed if it was the head. I read about that too, while searching the site. Before I bought, I think I asked here about anything major going wrong on these guys and nothing about the head was mentioned ... maybe it was too early (that was 2 years ago - I got mine used from my brother-in-law).

Would you suggest the Techron concentrate, or regular? I'll probably just go ahead and replace the plugs while I'm at it with the NGK iridiums (ILFR6A?) and do the fuel filter too.

Then I suppose it'll be on to the wires/coil packs ....

Any sensors I should check? Or would those show as a fault code?

I think I'll try to reset the codes w/ the scanner, then see what happens after I drive around a bit. I know it's still going to run rough at idle/idle speeds.

Thanks again!!!

mtnman82

Yeah, Buellwinkle, I had a feeling I might regret not buying that extended warranty ... got a chuckle from the expiration date comment

I'll add a can of MAF cleaner to the list for the parts store ... forgot to mention checking MAF stuff too in the last post (read about that in my searching too).

Is cleaning the injectors a service that can be found in a smaller town (like mine), or will I be sending them out if I want to have them done?

I know at least one of the code I saw was a pending code. Maybe that's why the check engine light went out?

I was wondering about a vacuum leak too. Maybe I'll take the air compressor to it to see if the intake system will hold ~10 psi? I don't hear any hissing/sucking noises, but it could be small.

Thanks!!!

mtnman82

Should I go one range cooler on the spark plugs? And if the normal plugs (NGK Iridium) are ILFR6A, what # is one range cooler? Thanks again!!

mtnman82

OK, here are what the plugs look like. They look maybe a little brown to me, but otherwise pretty good .... but then again, I'm not sure what they're supposed to look like.

What say you guys?? Do these look OK, or a little too brown? I'm still going to clean the MAF element to see if that helps. I put the Techron FI cleaner in the tank last night (had ~1/4 tank left), drove around ~10 miles, then put another 4 gallons of Chevron premium in the thank and drove around another half hour. No luck, same up/down idle.

At speed/under load, it seems to run just fine. Another thing I noticed is that when in neutral or park, if I try to hold the rpm's between 1K and 3K, I can't do it. The engine will speed up to 3K, or if I slowly try to take my foot off the gas, it will slow down to under 1K w/the stumbling idle.

rodngun762

I had a similar experience with the rough idle and check engine light 1 month ago, and it was the ignition (spark plug) wires themselves. A net set will cost around 2-300 dollars; they just wear out over time.

mtnman82

Thanks for the reply, rodngun!

So, does your C240 have coil packs? And the wire set you had replaced was what I have circled in the pic? That harness seems to go to quite a few things, including the coil packs. I wonder if there's a way to test it, and how hard it is to replace .....

Thanks again!!

C230 Sport Coup

Plugs look good. Replace 'em anyway as long as you're in their.
No need for cooler ones unless you have a boost kit.
Spark plug wires?
It's all low voltage!?

I think thats an issue on 6 cyl.
but not the 4 cyl. but not sure.

It's highly UNlikely that all coil packs would go bad at the same time.
Find that thread with the guy who had the vacuum leak...
he wasn't clear what was leaking..try to find out.
Something about from the intake to the SC....
take a look.

OK, that being said, ancient rule for repair is,
go back the last thing done.

Did you have ANY recent work done to the car?
If so, where? Then look in the area they would've been working, see if something got knocked loose.

And if that doesn't work, try to get the fuel pressure checked as Buell suggested. Also doubt fuel filter....but wouldn't hurt to change it.
50K miles is about right.
Order one online. MBZ will rape you.
Likely it's near the rear diff. Look to the left of the diff.
(thats where it's at on 2002) You'll need new clips, old ones you pry open with a screwdriver. Put the car on ramps, remove a couple screws from the bottom pan, prop it open with a screwdriver. Clamp the hoses so you don't get gas everywhere.
It's not a hard job, a little messy, uncomfortable (what job on a car isn't messy and uncomfortable? Ha, maybe coil pack...easiest fix known to mankind). Wear safety glasses so you don't get gas in your eyes.

C230 Sport Coup

Hey those are Bosch platinums....
car comes with Iridiums.
Who replaced the originals?

mtnman82

The car has ONLY been serviced by Smythe in San Jose, where my brother & sister-in-law bought it, and Sangera in Bakersfield after I bought it. No need for it to go anywhere but a dealer because it had the no-charge full service until just a couple months ago.

I was wondering about those wires, which is why I asked rodngun. I've heard others talk about replacing wires and I've been confused ... assumed it was other model(s) ... thanks for clearing that up a bit. I was thinking the same thing about all the coil packs going south at the same time.

I'll search again for that thread on the vacuum leak ... couldn't find it before. I need to see about taking the airbox all the way out to have a looksy at the intake/hoses - and I really, really need to get a service manual(!).

No service done in the past 5 months, and last thing it was in for was a faulty climate control module which was replaced. Good Lord, are there still vacuum lines attached to the climate control stuff???

I do hear a control valve or something from the passenger side foot area about a minute after I start the car up ... wonder if this is related ?

I have a fuel pressure tester/gauge kit, just don't see where the fuel rail is, or where a good place to attach a gauge would be. Again, I need to get a manual.

Where are some good places to order OEM parts on-line? Sure would be great if it were something simple like a fuel filter, but I'm never so lucky.

Thanks again!!!

mtnman82

OK, quandry of quandries .....

I was going to tackle taking the MAF out yesterday evening with the help of C230's thread on the subject. Had to go to the store to get a set of star sockets, then went to take the first bolt out, thru the plastic hole, only to find the socket is too big to fit thru the hole!!!

So this morning, out of frustration, I took the air filter out, unplugged the MAF, and sprayed the MAF cleaner thru the grate of the MAF tube. I went to work, and came back ~4 or so hours later. First I was worried because it wouldn't start up. It eventually did, and immediately gave me 'BAS' and 'ESP' - visit workshop messages. Now, I have posted before about these messages randomly popping up in the past few months, and then it will clear itself the next time I start the car and there will be no codes stored.

It definitely runs better than before. At times, it still does the very bad idle oscillation (oscillates between ~500 and 1000 rpm about once a second), but most of the time not as bad now. I can even leave it in gear at stop signs/lights most of the time now.

Soooooo, I'm thinking my idle problem is MAF related ... or so it would seem.

My quandry is that I have an appointment set up tomorrow at one of the nearest dealers (~2.5 hours away). It is convenient to drop it off tomorrow, but it will be a pain to pick it back up. I'm thinking about cancelling the appointment and trying to find the correct tool(s), taking stuff apart and cleaning the MAF myself. I'll probablly also order a new MAF (if I can find one reasonably priced on-line) and pop that in when it gets here.

Or, maybe I should bend over and let the stealer do his thing and be done with it ..... what would you guys do?

BadAssC230k

When your problem first started, was your car bogging big time, to the point of it shaking the whole car or to where it nearly stalled?

any huge lag in acceleration?


Only reason I ask is cause I might have the same issue.

mtnman82

It will sometimes bog, but mostly off idle/low rpm's it seems to run just fine. I was just driving it again, had just cleared the codes, and when I was taking off from a stop sign it bogged/stummbled/cut out/whatever you want to call it and the check engine light flashed. I'm going it's still off, but I bet I have some pending codes - same cylinder misfire codes I'm sure.

Soooo, just got done taking off the airbox, taking off the MAF sensor & spraying if off with MAF cleaner, cleaning everythign up real good, and putting everything back together again. I opted to replace the big hose clamp with a regular screw type. I also did the unthinkable - I disconnected the battery, no use of a 'quiescent current supply', which is probably just a small battery. No problems whatsoever with that. I only disconnected the ground, and I was very 'sure fingered' about it - i.e. I disconnected/reconnected in one swift/quick/sure-motioned move to aviod any chatter on the 12V line. I disconnected because that's what the star manual called for before disconnecting/reconnecting any of the electrical connections (MAF sensor, computer connectors, altitude sensor, etc.).

My car acts exactly the same. I'm really bummed. Of course, now I'm thinking I should have taken it in to the dealer on Wed because then it would have been done with. I have another appointment set up for the week after next, and I ordered a new MAF sensor which should be here by next weekend. I'm going to go ahead and replace the sensor anyway, just to be sure, and if that doesn't work then I have the appointment for a backup.

Maybe I'll get motivated and take pic's when I replace the MAF ... maybe ...

mtnman82

So, I did go ahead and order a new MAF sensor and install it. The car did seem to run better, but still had the rough idle issue. As I said earlier, seemed to run perfectly fine while driving, but up/down & rough idle, almost stalling at times at stop signs/lights (did a couple times). It would start right back up if it did stall. Have too many other things going on right now, so I bit the bullet and took it in to the dealer to check it out. I was suspecting a vacuum leak now from the way it acted, but didn't see/hear anything obvious. Dealer called me at ~830 in the moring to tell me they found a vacuum leak in the partial crankcase ventilation hose, which is buried underneath the intake manifold. The part itself plus new clamps was only ~$20, but they charged 5 hours labor to replace ($580). I'm guessing this is the same hose that went bad and was replaced in the other thread.

So there you have it. I did take a bunch of pic's when I replaced the MAF, so I'm hoping to get a write-up done and posted soon (never found one for an M271 engine). Also, I did get one of the STAR DVD's from Mercedes and I would definitely recommend it for anyone wanting to work on their car, or even just make sure the stealer isn't taking them for a ride - I wasn't sure about the 5 hours labor for this job until I looked at what it would take to get there. I'm still not sure it was a 5 hour job, but it definitely isn't a 1-2 hour job (book time, anyway).

BadAssC230k

Thats what happend to me! Only in reverse! My vaccum hose went out. Loss of power, etc etc. Went and had it replaced. A week and a half later it had to be back in the shop, for what felt like the same thing. Now its in for the MAF sensor, but was throwing [and apparently still is] giving a rough idle. The SA @ Smythe said it was possibly cam related.

Spoke with him on Monday afternoon [after the car has been down for the past 2 weeks] and he told me that the basically formatted the computer and reinstalled "NEW" Software and that they were waiting on an 'ESN Key' from Germany, basically to activate everything and make sure everything is seen via the new software.

And here I sit... With an 07 C230 loaner... Almost 3k in mods that have yet to be installed... WITHOUT MY car

mtnman82

Hey BadAss, please let us know how it all turns out, and what was going on. You've got me a little worried now ...... I hope nothing else is going to go wrong.

So they replaced the MAF sensor, and also flashed the computer ... those are the only corrective actions they're taking? I'm wondering why the need to flash the computer????

Is this being done under warranty?

Had your car been in for service before (I assume so ......)? Ever had the computer flashed before? Supposedly my computer had been updated at one point, but I'm not sure.

BTW, my '03 C230k came from Smythe in San Jose too (some in-law's bought it there new, we bought it from them).

BadAssC230k

at this point the SA "cant give me an answer" cause he doesnt know whats going on. Yeah tell me about being worried. They replaced the MAF sensor which cleared the CEL. However there is still a rough idle issue, from what I'm hearing.

From what it sounded like, they flashed the ecu and updated it [made it sound like Windows XP Service Pack 3 update, lol]. Yes its being done under warranty, thankfully. But its DEFINETLY making me think about getting rid of it at 100k [im at 62k now]. Im definetly on edge about the whole thing and VERY concearned with what my upcoming options may be.

The car was service for the vaccum hose a week and a half before, seemingly, the MAF & rough idle showed its ugly face. To my knowledge the ecu has never been flashed before. But now its making me worry if I should not have it done to get tuned [SI, Powerchip, etc].

drexappeal

J, what the hell? Sorry to hear the issues you've been having.

BadAssC230k

yeah seriously! Im not happy about it either. worst case scenario, i'd be gettin a new motor?! lol I can only wish


hell, just slip in the 3,498cc V6 and a 7spd tranny. very RAWR power! Ahh, one can only imagine/hope.

BadAssC230k

UPDATE

Just got off the phone with the S.A. from Smythe. Basically what’s going is that, they flashed the ECU with newer software. Seems the newer software is sending out improper calibrations for A/F mixture. They now say it’s running too rich. MB in Germany is making Smythe basically jump through hoops before they declare the ECU needs to be replaced. The firmware upgrades could have fried the ECU during the updates and/or the ECU is having conflicting problems with recognizing the newer software, in turn messing up the correct ECU calibrations.

Seems kinda funny since I was sitting here thinking about having the ECU tuned anyways. Now I’m not sure if it’s a smart idea. I mean I’m sure once it’s done, it will be fine, but I’ll still have the urge to want to mod it. But I definitely don’t want to do anything that’s detrimental to my car/engine.

patrick_y

Jay; I'm sorry to hear you're having so many difficulties.

I can only hope that you are enjoying your loaner vehicle and that the staff at Smythe is treating you better than the staff at Mercedes-Benz of Pleasanton.

RES

I'm at 87,000 miles and having the same problems for the last two weeks. Thought about changing the MAF, but now I think I need to try a few more things first. I'm waiting for Sunman to come up again so we can scan this thing to see if anything comes up?

BadAssC230k

that sucks! yeah, my SA said "we've spent about 20 hours on there car" and they still havent exactly found out whats going on. Can you imagine having to pay for that? at between $90-$110 per hour. OMG!